Unidirectional Microphone based Wireless Recorder for the Respiration Sound

Abstract

The wireless recorder for heart and lung sounds is intuitively convenient to the medical doctors and the patients for its portability which makes the auscultation be possible in a certain range. Such a recorder facilitates increased patient movement (postures and exercises) during diagnosis. Therefore, a wireless communication system for lung sound recording has been developed in this study. Two unidirectional microphones (SM35 and Beta 98H/C, Shure), a wireless body pack transmitter (PGXD1, Shure), and a wireless receiver (PGXD4, Shure) were used in our recording system. The detected sound was transmitted to a mixing console (MG06, Yamaha) for amplification. The system characteristics are as follows: (1) offers excellent low-frequency response, (2) has unidirectional microphone sensing, (3) blocks noise from the environment, (4) records sounds of moving and exercising people, and (5) records other physiological sounds. All of SNREN>35 in tests under the environmental noises in the range of 25 to 40 dB encouraged us to neglect the influences of the environmental noise. The findings strongly recommend that the proposed recording system be adopted by groups researching lung sounds because it reduces the number of complex devices and algorithms necessary for noise reduction, offers a high SNR, and facilitates device use in various environments. Furthermore, the developed system can be used to record lung sounds because of its excellent low-frequency response, especially, using the instrumentation microphone.